1. Field of the Invention
The present invention concerns a universal procedure, for making sheets that are completely or incompletely perforated. The sheet may be pierced by multiple perforations, or may present, a drawing with motifs in hollow or relief.
It is well understood that this new procedure may be used on a sheet of material of any type, Examples being paper, cardboard, unwoven fabric, film, a sheet of plastic material or a sheet of wood or plywood.
The invention equally concerns new industrial products obtained following this method, and possessing original characteristics that cannot possibly be obtained with the traditional known methods.
2. Prior Art
It is known to make unwoven material, presenting some perforations or having areas of reduced density fibers, notably for application in the medical or hospital field realm, for wiping, for filtration, for tea bags etc. For this, it is known, for example in the French letters patent 2,068,676, to circulate a fiber cloth on the porous linen of a support carrier. The cloth is treated while passing under a perforated rotating cylinder, at the interior, where a hydraulic injector is arranged. This injector projects under pressure, a continued curtain of water, which crosses the holes of the perforated cylinder, creating jets of water whose dimension corresponds to that of the perforations. These water jets cross the fiber cloth while reproducing the form of the holes of the cylinder on the material before being collected by a suction case situated under the carrier linen, underneath the rotating cylinder.
Such a known apparatus presents major disadvantages. In effect, the use of an injector supplying a continuous wave of water on all the generators of the cylinder expressed by the release of a considerable flow of water inside of it. The perforated parts of the cylinder represent but a weak part of the surface of as a result presents a practically insolvable problem, which is the elimination at the interior of the cylinder, of the water thrown back by the full parts.
In order to limit the problem, one is driven to lessen the quantity of water emitted by the injector, or reduce the depth of the curtain of water, and the pressure of the water. This results in obtaining at the outside of the cylinder, some water sprays that do not possess a sufficient kinetic energy for perforating some materials of the plastic film type, fabrics, even thick paper.
The water that rebounds on the filled parts of the cylinder the length of the same generator equally disturbs the cohesion of the water curtain and considerably affects the kinetic energy of the water sprays emitted by the cylinder. In effect, the water has a tendency to fall again in a random manner in the cylinder after rebounding. This is evidenced by a disorderly accumulation of water the length of the generator in the cylinder situated to the right of the water curtain.
This excess water acts as a shock absorber against the water emitted by the injector which reduces its kinetic energy to a level such that it becomes insufficient for assuring a uniform marking of the sheet at this point. As a result, areas appear on the treated sheet presenting a washed out quality and the pattern of perforations is poorly defined.
The present invention avoids these disadvantages, realizing a machine practically universal for making papers, unwoven fabrics, textiles or perforated plastic films or possessing motifs in hollow or relief.